Conventional formation of viral particle-like structures has involved recovering virus-like particles formed within cells.
In some methods, the virus-like particles are purified from the cells and are first dissociated into particle structure units (for example, VP1 pentamers in the case of SV40 virus), and then reconstituted into virus-like particles in a test tube.
Conventional reconstituting methods have been conducted under non-physiological conditions with high salt concentration, but because of problems such as inactivation or poor solvent solubility of bioactive substances included in the particles, the conditions have not been suitable for taking up bioactive substances into particles. Moreover, it has been difficult to efficiently reconstitute virus-like particles of uniform size by such methods.